In order to achieve power losses that are as small as possible, integrated circuits (ICs) for driving laser diodes are being developed for ever decreasing supply voltages. A further motivation for smaller supply voltages is constituted by breakdown criteria of many of the integrated components used.
The operating point of a laser diode to be driven is set by a threshold current and a modulation current, the modulation current representing the data stream. The currents generate a voltage drop across the laser diode. The voltage drop across the diode may be so large that the laser can no longer be driven directly by the laser driver IC on account of the limiting supply voltage.
If the voltage drop across the laser diode is so large that the laser can no longer be driven directly by the laser driver IC on account of the limited supply voltage or the required voltage drops across the driver transistors, then it is known to cause the modulation of the laser diode to be effected by means of a coupling capacitance. In the case of modulation and transmission of the data in the radiofrequency range, however, losses and mismatches due to parasitic elements occur on the coupling paths both from the modulation output of the laser driver IC to the coupling capacitor and from the coupling capacitor to the laser diode coupling unit. Said parasitic units may be, inter alia, bonding wire inductances and pad capacitances.
DD-A-159 584 discloses an intermittently radiating light-emitting or laser diode arrangement in which a AMENDED SHEET light-emitting diode chip is arranged on a carrier. A capacitance to which a signal is applied is situated between the carrier and the light-emitting diode chip. The carrier is an integrated circuit.